1. Field of the Invention
This invention relates generally to devices for skimming oil from the surface of water.
More particularly, this invention relates to a single drum skimmer and a weir skimmer for recovering all types of oil from a surface of a body of water, such as oceans, lakes, ponds, rivers and the like, and in particular to an oil retriever that is maneuverable independently on water and can operate efficiently to assist in cleaning up oil spills or other bodies of water containing oil in suspension.
2. Description of the Prior Art
Environment awareness is becoming increasingly more prevalent in response to preservation of the global ecology. The advent of offshore drilling platforms and the use of supertankers to transport crude oil and the like has greatly increased the likelihood and magnitude of catastrophic damage to the oceans lakes, rivers, and ponds by contamination due to spillage on these bodies of water. The damage and destruction from these pollutants can wreak havoc to the ecology that can potentially take decades to recover.
Current methods of cleaning polluted waters have been unsatisfactory, particularly when the conditions have been less than ideal. Speed in cleaning spills is critical due to the rapid spreading of the floating surface material by the currents and wind. Delays may occur in cleaning isolated sites due to problems in transporting the equipment to the site. The turbulence of the oceans or other bodies of water often prevents the equipment from being used.
The apparatus currently used are simple mechanisms such as handheld devices or throwing rags or straw on the surface to absorb the material which are ineffective in cleaning large areas or else complex devices which are expensive to manufacture and to maintain. The complexes devices normally are not effective in completely removing pollutants from the surfaces, particularly when there is a wide depth of the pollutants, turbulence of the surfaces and difficulties in the site conditions.
Other methods utilizing chemicals or burning of the floating material are dangerous to the environment and are simply not feasible for large areas that may need to be cleaned. There presently exists a need for a system to quickly recover floating material such as pollutants or debris from the surfaces of bodies of water without regard to the demands of the particular site conditions.
There are a variety of skimming devices in the prior art. One such skimmer is a weir skimmer, which typically comprises a barrier wall of adjustable height which allows oil floating on water to flow over the wall and into a collection trough while excluding water. Recovered oil is then continuously pumped from the collection trough to a storage or transport means. Weir skimmers operate well in calm water with large or contained spills which produce a relatively thick oil layer.
Disc skimmers ordinarily include a plurality of discs spaced apart coaxially along a rotating shaft which is supported by floats to position the lower portion of the discs in the water. Oil contacts and adheres to the rotating discs is removed by blades or wipers which direct the collected oil into a sump or other collection means.
A mop skimmer, or rope skimmer, is arranged to contact the oil film with an absorbent or filamentous member to which the oil clings. The oil-heavy member is then passed between rollers which squeeze out and collect the oil.
Drum skimmers have also been used for removal of oil and other hydrocarbons from water surfaces. A drum skimmer consists of one or more large rollers, or drums, which rotate partly submerged in water. Oil attaches to the drum surface as the drum rotates through the oil-water interface. The attached oil is then removed by squeezing or scraping the oil from the drum surface.
One example of such a device is shown in the Wilson et al U.S. Pat. No. 4,957,636 which discloses a dual drum skimmer arranged along a common axis which pick up oil and deposit it in a collection trough. Two relatively large diameter drums are mounted on a frame and arranged to rotate about a common axis. A collection trough, which forms the front of the frame, receives oil scraped from the rotating drums. Collected oil is passed to a reservoir trough, which forms the back of the frame, through channels between the two drums and the drum ends. The reservoir trough and the drums are sized to provide all of the buoyancy necessary to float the device.
U.S Pat. No. 3,612,277 to Van Stavern discloses a rotatable drum type of oil skimmer which is continually rotated to pick up a film of oil and water on the surface of the drum, having a supplemental or transfer drum located substantially above the oil slick and well out of contact with the oil slick, picking up the oil from the first drum and depositing it in a trough.
U.S. Pat. No. 5,043,064 to Abell et al discloses a pair of hulls interconnected by a deck structure. A perforated drum has a covering which is comprised of an oleophilic material. The covering in an alternative embodiment has bristles or brushes. A doctor blade contacts the covering of the drum to remove oil or debris from the drum for deposit into a sump.
U.S. Pat. No. 5,030,363 to Pole discloses an oil retriever with interchangeable collection tanks. Across the front of pontoons, a cylindrically shaped drum is rotated about its longitudinal axis by a reversible, variable speed motor. There are two scrapers extending along the entire rearward side of the drum. U.S Pat. No. 4,978,448 to Terekomos discloses a system using an elongated scoop, and U.S. Pat. No. 5,137,630 to Eklund discloses a system using brush discs and a comb member for separating oil from the brush discs.
None of the above prior art devices are as easily transportable, rugged in construction, nor as effective in cleaning up large areas as the instant invention or else are complex devices which are more expensive to manufacture and to maintain.